OPR-G329-TJ-16Approaches to SavannahApproaches to SavannahNOAA Ship THOMAS JEFFERSONH129601Object DetectionApproaches to SavannahSouth CarolinaUnited States200002016Chris van Westendorp, CDR/NOAANavigable Area2016-09-162016-11-072016-11-17Multibeam Echo SounderSide Scan SonarmetersWorld Geodetic System 1984 (WGS84) - Universal Transverse Mercator (UTM)UTCAtlantic Hydrographic BranchNOAAHydrographic survey H12960 was completed as specified by hydrographic survey project instructions OPR-G329-TJ-16, signed 16 September 2016. This survey extends approximately 12 to 22 nautical miles east of Tybee Island Light in the approaches to Savannah, Georgia (see Figure 1).32.012045277880.613744722231.921811111180.4053038889H12960 Survey Extentsfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/H12960%20Survey%20Limits.pngSurvey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.The purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products in the approach to the Savannah Outer Harbor Channel. In order to allow deeper draft ships such as Panamax ships which could draft 39.5 feet, the Savannah Harbor channels are being deepened to 49 feet at Mean Lower Low Water (MLLW), with a controlling depth of 47 feet. The main driver for this project is based on a request from the Savannah Pilots Association. The survey area will also address concerns about migrating sand shoals.The entire survey is adequate to supersede previous data.All depths within H12960200% Side Scan Sonar (SSS) coverage with concurrent Multibeam Echosounder (MBES) depth and backscatter dataSurvey coverage was in accordance with the requirements listed above and in the HSSD (see Figures 2, 3, and 4).100% SSS Coverage Mosaicfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/H12960%20SSS%20100%20Mosaic.png200% SSS Coverage Mosaicfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/H12960%20SSS%20200%20Mosaic.pngMultibeam coverage acquired with concurrent 200% SSS.file:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/H12960_MB_Coverage.pngS222000001357.7057.00000001357.7057.004.19000043.612016-11-062016-11-072016-11-082016-11-092016-11-102016-11-112016-11-122016-11-132016-11-142016-11-152016-11-162016-11-17Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, quality control procedures and data processing methods. Additional information to supplement sounding and survey data, and any deviations from the DAPR are discussed in the following sections.S22220815KongsbergEM2040MBESKlein5000 V2SSSApplanixPOS/MV v5Positioning and Attitude SystemValeportModus SVSSound Speed SystemRolls RoyceBrooke Ocean Moving Vessel ProfilerSound Speed SystemSeabirdSeacat 19+Conductivity, Temperature, and Depth SensorCrosslines were compared to mainscheme using a difference surface, created in ESRI ArcMap 10.3. A 50cm Combined Uncertainty and Bathymetric Estimator (CUBE) surface was created using strictly mainscheme lines, while a second 50cm CUBE surface was created using only crosslines. The two surfaces were then differenced. 95.86% of nodes agree within +/- 0.25m, and 99.99% of nodes agree within +/- 0.50m. The mean was -0.03m and the standard deviation was 0.12m (see Figure 5). Survey H12960 crossline analysis complies with section 5.2.4.3 of the HSSD (2016). Mainscheme to crossline difference surface statisticsfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/crossline%20comparison%20H12960.PNG00.148ERS via VDATUMS2224.01.00.2Total Propagated Uncertainty values for survey H12960 were derived using a combination of a priori uncertainty estimates for vessel elevation, equipment, motion, vessel characteristics, the VDatum separation model used to reduce soundings to chart datum, and field assigned values for sound speed uncertainties. Uncertainties for sonar mounting and vessel speed were based on Appendix 4, table 4.9 of the NOAA Field Procedures Manual (FPM) (ed 2014). These were applied to the data via the CARIS HIPS Hydrographic Vessel File (.hvf). The uncertainty associated with the VDatum separation model was supplied by the Hydrographic Surveys Division’s Operations Branch, and is listed under the Zoning (see table 6). Finally, the uncertainty associated with sound speed measurements were based on the frequency and location of CTD casts, in accordance with the guidance set by Appendix 4 of the FPM (ed 2014) (see Table 7). Total Propagated Uncertainty was then evaluated to ensure compliance with section 5.1.3 of NOAA's Hydrographic Surveys Specifications and Deliverables. First, the maximum allowable uncertainty for each node was calculated using the equation: -Uncertainty/((0.25+((Depth*0.013)^2))^0.5). Second, the ratio between actual uncertainty and maximum allowed uncertainty was found for each node. The resulting 'TVU_QC' layer was filtered using a color map to show any areas where actual uncertainty exceeded the maximum allowed uncertainty. 100% of grid nodes of the 0.5m MBES CUBE surface meet IHO uncertainty requirements for IHO Order 1a surveys as seen in the Pydro CSAR QA tool output plots (see Figure 6).Uncertainty Standardsfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/Uncertainty%20Standards.pngH12960 had one contemporary junction survey.F00690200002016NOAA Ship THOMAS JEFFERSONSW H12960 overlaps a portion of F00690, which is a multibeam reconnaissance survey of crosslines covering the entire project area. Some F00690 lines were used as crosslines in the H12960 crossline comparison. See the crossline comparison section (Section B.2) for more information. Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. Depth artifact on leeward side of EM2040 MBES swathA depth artifact on the leeward side of the MBES swath was observed during sonar acceptance testing of NOAA Ship Thomas Jefferson's recently acquired EM2040 MBES. H12960 was subsequently the first S222 MBES survey after the sonar acceptance testing. To mitigate the severity of the depth artifact, S222 operated the EM2040 in single sector mode, and a reduced swath angle of 45° on each side of nadir. While this was successful in reducing the severity of the the artifact to at most 10-20cm on the roughest days, well below the survey's allowable TVU, these anomalies still manifested throughout the MBES dataset, especially during days with relatively rougher sea states (see Figures 7, 8, and 9). Additional information can be found in the Hydrographic Systems and Technology Branch testing report, forwarded as part of the DAPR.Leeward side MBES artifact seen in slope child layer created in ArcMap 10.3, and viewed in Caris HIPS 9.1.9file:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/Leeward%20side%20MBES%20artifact%20in%20depth%20slope%20plot.PNGMBES artifact seen in depth layer with 15x vertical exaggerationfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/Artifact_Depth_15VertExag.pngMBES artifact seen in 2D subset along-track orientationfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/Artifact_Depth_2D.pngSea-State affected soundingsOn day numbers 312, 313, 317, and 318, the survey vessel experienced rough seas leading to several MBES blowouts. These blowouts left several gaps in the depth grid deliverable. However, these gaps were also covered by 100% and 200% SSS coverage, and no evidence of significant features were found therein (see Figure 10).Sea-state affected soundingsfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/sea%20state%20affected%20soundings.PNGSmall data gaps between MBES line filesSmall data gaps (~2.5m wide) between the end and start of MBES line files exist throughout the survey. However, these gaps were also covered by 100% and 200% SSS coverage, and no evidence of significant features were found therein (see Figure 11).Small data gaps between MBES line filesfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/timing%20gap%20in%20MBES%20data.PNGSmall data gaps between SSS line files in SSS MosaicSmall data gaps (~2.5m wide) between the end and start of SSS line files exist throughout the survey. However, these gaps were also covered by the other 100% or 200% SSS coverage, and no evidence of significant features were found therein (see Figure 12).Small data gaps between SSS line files displayed in H12960_SSS_100.csar mosaicfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/SSS_Timing_Gaps.jpgApproximately every 30 minutesSound Speed measurements of the water-column were conducted approximately every 30 minutes using a Moving Vessel Profiler (MVP), and more frequently in areas or times of more dynamic fluctuations in sound speed. When the MVP was in maintenance, Conductivity, Temperature, and Density (CTD) casts were taken at a frequency of ~4 hours, as seen in part of day numbers 315 and 321. Figure 13 shows acquired data colored by sound speed cast. H12960 geographic distribution of sound speed casts from S222file:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/Geographic%20distribution%20of%20sound%20speed%20Casts.PNGRefer to Section A.4 and B.1.2. of this report for survey equipment and methods used to meet coverage requirements for this project. All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR.Backscatter was processed by the field unit using Fledermaus FMGT software. CarisHIPS and SIPS9.1.9QPSFledermaus FMGT7.6.4NOAA Profile V_5_4H12960_MB_50cm_MLLW_FinalCUBE0.512.5721.92NOAA_0.5mObject DetectionH12960_SSS_100SSS Mosaic100N/A100% SSSH12960_SSS_200SSS Mosaic100N/A200% SSSThe submitted multibeam 50cm surface for survey H12960 meets density requirements for object detection as described in section 5.2.2.2 of the HSSD 2016 (see Figure 14). For further discussion, see section A.4 of this report. A very small area of the surveyed depths exceeded 20m. A deviation from the HSSD was approved by the HSD Project Manager to include all depths of the survey in a single deliverable 50cm surface, although some surveyed depths exceeded 20m. Object Detection Density Requirements Plot for H12960file:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/Object%20Detection%20Coverage%20Plot.pngSurface FliersFliers were detected using HSTB Pydro tools, as well as an in-house ArcGIS script used to augment the Pydro QC Tools. H12866_MB_0.5m_MLLW_final grid was scanned for fliers at 50cm tolerance, and yielded one potential flier. After review, the remaining flagged node was determined to be a valid object, as shown in Figure 15.H12960 HSTB Auto QC Tools Flier Finder Resultsfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/flier%20finder%20results%202.PNGPer section 5.1.2.3 of the FPM (2014 ed), no Horizontal and Vertical Control Report has been generated for Survey H12960.Mean Lower Low WaterERS via VDATUMg329_full_area_sep_xysep.csarSounding elevations relative to the ellipsoid were collected through real time precise point positioning (RT3P) via Fugro Marinestar services, as detailed in the DAPR. World Geodetic System 1984 (WGS84)Universal Transverse Mercator (UTM) 17NHorizontal positioning was collected through real time precise point positioning (RT3P) via Fugro Marinestar services, as detailed in the DAPR. Surveyed soundings were compared to existing charted soundings by two separate methods to ensure agreement in results. The first method differenced surveyed soundings to an interpolated digital elevation model (DEM) created from the archived survey-scale soundings of most recently charted historical National Ocean Service (NOS) surveys. The second method used PydroExplorer's QC Tools DtoN Scanner application to compare current ENC soundings to a dense shoal-biased sounding selection from H12960. The first method involved downloading archived survey-scale soundings through the National Centers for Environmental Information (NCEI) Data Extract System, or NEXT-web data extraction portal. A DEM representative of the historical surveys was created using ESRI ArcMap 10.3 Spatial Analyst Extension Natural Neighbor interpolation tool, gridded to 4m (see Figure 16). The most recent hydrographic surveys in the project area were completed between 1972 and 2005; the majority of the project area was completed between 1994 and 1995 by NOAA Ship Whiting, with a corresponding encoded CATZOC value of A2 on NOAA ENC US5GA20M (see Figure 17). The historical DEM was subtracted from the H12960 50cm depth CUBE grid to create a difference surface, with a mean difference -0.050m and a standard deviation of 0.196m. Discrete nodes with differences greater than 1m were analyzed for possible Dangers to Navigation (DtoNs), and general depth changes of large features such as shoals or sand waves were also investigated. Most grid nodes with a difference greater than 1m correlated with crests of large sand forms. This is to be expected, as small horizontal positioning and sounding technology differences can result in large apparent vertical differences (see Figure 18). From this analysis, the sand shoals appear largely stable, with very little observable migration patterns from past surveys. The second method involved the PydroExplorer QC Tools DtoN Scanner, which identifies survey soundings with a shoal discrepancy as compared to the chart, evaluated via the "triangle rule." The tool creates a triangulated irregular network (TIN) from the ENC soundings (and feature value of soundings, if present). Survey soundings are categorized within the TIN triangles, and if any survey sounding is shallower than the three triangle vertex soundings, it is flagged. Results from H12960 compared to ENC soundings and features from US5GA20M and US4SC22M yielded several possible chart discrepancies (see Figure 19). However, upon further review, most survey soundings flagged as possible chart discrepancies would not be flagged if the TIN were to be drawn in a different but equally legitimate configuration, such as in the approximate location of 31°58'3.64"N 080°34'9.48"W. This was confirmed by running the historical surveys DEM through the DtoN Scanner Tool, which highlighted almost exactly the same areas as possible chart discrepancies in H12960 (see Figure 20). With the exception of the area mentioned before, no survey soundings varied from the largest scale charts by more than one meter. The 60 foot depth curve is the only depth curve that exists in the charted area of Survey H12960. Upon review of a shoal-biased depth contour dataset created in Caris HIPS 9.1.9, there is general agreement with the existing depth curves (see Figure 21).Historical Surveys DEM creation using ArcMap 10.3file:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/historical%20DEM%20creation.pngAge of latest historical surveys in Project Areafile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/historical%20survey%20ages.pngPosition of depth differences between historical DEM and H12960 greater than 1m. Difference values are shown in red. file:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/DEM%20diff%20greater%20than%201m.pngH12960 DtoN Scan chart discrepancy results greater than 1m, near 31°58'3.64"N 080°34'9.48"Wfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/H12960%20dton%20scan%20results.pngHistorical Survey DEM DtoN Scan chart discrepancy results greater than 1m near 31°58'3.64"N 080°34'9.48"Wfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/Historical%20DEM%20dton%20scan%20results%20zoom.pngSurvey contours compared to charted depth curvesfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/Contours_ENC.jpg1150529004000052014-082017-01-242017-02-11NOAA Chart 11505 covers almost the entire area of survey H12960 at a scale of 1:40,000. Any changes to assigned features derived from the ENC can be found in the Final Feature File included with this report. Charted depths generally agreed with surveyed depths within two feet, with exceptions noted in Section D.1 of this report. 1151325380000272013-122017-01-242017-02-11NOAA Chart 11513 covers the eastern area of survey H12960 at a scale of 1:80,000. Any changes to assigned features derived from the ENC can be found in the Final Feature File included with this report. Charted depths generally agreed with surveyed depths within two feet, with exceptions noted in Section D.1 of this report. US5GA20M40000432017-01-172017-01-17falseNOAA ENC US5GA20M covers almost the entire area of survey H12960 at a scale of 1:40,000. Any changes to assigned features derived from the ENC can be found in the Final Feature File included with this report. Charted depths generally agreed with surveyed depths within two feet, with exceptions noted in Section D.1 of this report. US4SC22M80000192017-01-172017-01-17falseNOAA ENC US4SC22M covers the eastern area of survey H12960 at a scale of 1:80,000. Any changes to assigned features derived from the ENC can be found in the Final Feature File included with this report. Charted depths generally agreed with surveyed depths within two feet, with exceptions noted in Section D.1 of this report. No Maritime Boundary Points were assigned for this survey.One charted 55-foot obstruction existed within the limits of survey H12960. For full details on the feature investigation, see the Final Feature File submitted with this report. No uncharted features exist for this survey.No Danger to Navigation Reports were submitted for this survey.No shoals or potentially hazardous features exist for this survey.No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channel and range lines within the survey limits.No bottom samples were required for this survey.Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work.For more information on the comparison of H12960 with prior surveys, refer to section D.1 of this report. The Aid to Navigation (ATON) Y "T" Fl Y 2.5s buoy was within the H12960 project area, and found off station and extinguished. The discrepancy was immediately reported to the US Coast Guard through the online web ATON discrepancy reporting tool (see Figure 22).ATON discrepancy report sent to US Coast Guard for buoy Y "T" Fl Y 2.5sfile:///H:/Surveys/OPR-G329-TJ-16%20Approaches%20to%20Savannah%20River/H12960/Separates/Descriptive_Report/Report/DR_Images/ATON%20discrepancy%20sumbitted%20via%20NAVCEN%20website.pngNo overhead features exist for this survey.No submarine features exist for this survey.No ferry routes or terminals exist for this survey.No platforms exist for this survey.For full details, see the Final Feature File submitted with this report. No present or planned construction or dredging exist within the survey limits.No new surveys or further investigations are recommended for this area.No new insets are recommended for this area.As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports.All field sheets, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch.The survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys and Specifications Deliverables Manual, Field Procedures Manual, Letter Instructions, and all HSD Technical Directives. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies noted in the Descriptive Report.Chris van Westendorp, CDR/NOAAChief of Party2017-02-21Matthew Forrest, LT/NOAAField Operations Officer2017-02-21Alex LigonSheet Manager2017-02-21Anthony Klemm, LT/NOAASheet Manager2017-02-21Dale Gump, ENS/NOAASheet Manager2017-02-21